What is a suitable lossless codec to export from Natron?

I need to render something from Natron and I want to do it losslessly (or at least at very high fidelity) because it is very short. I will be importing the video thus created into Sony Vegas 13. What would be the right combination of codec and container to use? The ones I’ve tried so far Vegas didn’t like.

Use ProRes and install QuickTime for use in Vegas.

That’s at least what I used to do.